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Whey protein refers to the globules of protein suspended in whey, the liquid that remains after straining of curdled milk. The whey solution consists of vitamins, minerals, lactose, protein, and trace amounts of fat. Processing of whey to remove the sugars and fats leaves the highly concentrated whey protein solution. One of three main forms of whey protein, whey protein isolate contains greater than 90 percent milk proteins. Protein derived from whey protein isolate is one of the most biologically available sources of amino acids, because it is easily digested, adsorbed, and assimilated for muscle building.
Protein is a dietary component that fulfills a number of vital roles in the body including body cell repair, muscle and bone formation and repair, energy production, and metabolic control. Whey protein isolate is a natural, complete protein, with all the essential amino acids required by the body. It is also the richest source of branched chain amino acids, such as leucine, isoleucine, and valine. During and following exercise, branched chain amino acids are absorbed directly into the skeletal muscles instead of being metabolized in the liver, ultimately increasing muscle mass. In addition, during exercise, whey helps dilates blood vessels to promote better blood flow and transport of nutrients to the muscle tissues.
Leucine plays a key role in starting the protein synthesis pathway. When the diet includes large quantities of leucine, such as with whey protein isolate supplementation, rapid protein production speeds recovery and acclimation to physical stress or exercise. In addition, a large amount of whey protein increases cellular glutathione, an antioxidant that protects the body from free radical damage and toxins. Some animal studies suggest that whey proteins potentially reduce the risk of cancer, particularly breast cancer. They also increase the immune activity of T-cells in the blood.
Whey protein isolate supplements contain not only a high concentration of branched chain amino acids but also the correct proportion of the other amino acids. Ingestion of a complete, balanced protein results in better nitrogen retention, beneficial for bodybuilding. Positive nitrogen balance can be achieved by consuming approximately 2.2 grams (0.078 ounce) of protein per kilogram (2.2 pounds)of body weight each day. Nutritionists recommend that the daily allowance of dietary protein be spread out over four to six small meals per day. As a supplement, the whey protein isolate is typically mixed into 0.24 liters (8 fluid ounces) of cold water, skim milk or another beverage.
There are few side effects associated with whey protein supplementation. Too much protein in the diet, however, can potentially overload the liver and kidneys. Although the one gram per pound of body weight applies to bodybuilders and extreme athletes, those who are not actively engaged in strenuous exercise should take less. Lactose-intolerant individuals can still have problems with whey protein isolate, although the isolate only contains about one percent lactose.